Research Finds Brain's Navigation System May Help Detect Early Alzheimer's

A new study may help patients at risk of Alzheimer's disease detect early signs of the condition by looking at their brains' navigational cells. Diagnosing memory loss conditions early is important, as it allows people to better plan for the future and understand their illness. They may also have more opportunities to benefit from available treatments.

Very few adults who are living with dementia, including Alzheimer's disease, have been properly diagnosed by their doctors. In fact, the Alzheimer's Association reported that between 2000 and 2005, of the millions of people with memory-loss conditions, only 35 percent had an official diagnosis on their medical records. Physicians and patients must work together to identify the early warning signs of Alzheimer's disease, as the source pointed out that many of its symptoms are reversible when caused by treatable factors like depression, thyroid problems or vitamin deficiencies.

The group of scientists conducted the new study in hopes of finding a more effective way to identify Alzheimer's disease earlier. The results, published in the online journal Science, showed that those who are at high risk of developing Alzheimer's have slower acting neurons in their brain compared to healthy adults.

Alzheimer's gene affects brain's internal navigation
The neurons that work as the brain's internal navigation system are called grid cells and are located in the entorhinal cortex. In addition to playing a large role in navigation, they also have a part in controlling memory. Forbes noted that grid cells work with people's memory to track movements and establish mental maps of familiar places so that it's possible to navigate them without visual cues. The discovery of the brain's navigational system is a recent development that earned the 2014 Nobel Peace Prize in Physiology or Medicine.

The scientists took this recent discovery and findings from previous research to conduct their experiment. The prior studies had shown that those with a variant of the gene - APOE-e4 - linked to Alzheimer's had a higher chance of developing abnormalities in their entorhinal cortex than those without it.

Two groups of young adults without any signs of memory loss participated in the study. One group carried the gene variant associated with Alzheimer's and the other didn't. Volunteers in both groups were asked to find their way through a virtual space consisting of a large circular area with mountains and blue sky in the distance. While they navigated the maze, they were also tasked with completing activities, such as picking up basketballs and returning them to their original locations later in the study. Meanwhile, the scientists monitored their brain activity.

Results provide gateway to new therapies
Just as the researchers had predicted, the participants with the gene variant showed less activity in their grid cells than the group without the gene. However, the scientists were surprised to find that both groups performed well when navigating through the virtual maze. The only difference was the volunteers with the Alzheimer's gene stayed near the edges of the maze while the others used the entire space to navigate.

Neuroscientist Nikolai Axmacher, a study author from Ruhr University in Bochum, Germany, explained that the participants with less grid cell activity relied more on the hippocampus - a brain region that contributes to memory formation - to make up for this inactivity. This is likely the reason for the different strategies both groups took when navigating through the maze, showing that properly functioning grid cells are correlated with human spatial behavior.

While the scientists noted that this navigational test probably won't be used as an early Alzheimer's detector any time soon, the insights into the way the brain works when impacted by the Alzheimer's gene has taken researchers one step closer to developing effective preventative therapies.